This is an interesting one
I do a bit of sculpture and am very into shape and form etc... For what it's worth, I can remember years and years ago (well, about 18 yrs ago!) being on holiday in France as a kid and being amazed my those little glass bottles of Orangina....it was the first time I had seen anything like it and I remember thinking the bottles really stood out in the supermarches and I was so excited about trying it for myself!
Basically, the first thing you need is an eyecatching, innovative shape -preferably something that hasn't been done before. Secondly, the bottle also needs to be user-friendly - it needs to be easliy grasped and not an awkward shape for the hand. The type if material you use in fabricating the bottle is also important in this regard. I'm more or less of the opinion that as much has been done with the plastic bottle as is possible, for the next few years anyway, and I would be an advocate of a glass bottle approach. Glass has the benefit of being more easily recyclable too, which is important to many consumers nowadays. Glass is also a more sculptural material, and aesthetically more pleasing to the eye than plastic. Coloured glass is also a possibility - purples and blues are very good colours to go for if the product is a beverage, and I would stay away from reds, yellows and greens. However, glass is less malleable than plastic and so a glass bottle may not have the same "grasp factor" as a plastic one.
Hope this helps
Noor